The layered structure of bismuth telluride affords greater flexibility for stress manipulation, which has emerged as a promising approach to modulating thermoelectric (TE) properties of thin films. Herein, high-quality Bi 2 Te 3 thin films are prepared by the one-step magnetron sputtering, showing considerable potential in large-scale fabrication. By simply tilting the incident angle α , the TE performance of the as-prepared films can be significantly improved. Notably, the presence of massive intragranular defects helps to decrease the macroscale stress stored by the momentum of sputtered atoms. Benefiting from this stress reduction, the carrier concentration and effective mass are simultaneously enhanced, leading to increased electrical conductivity with limited changes to Seebeck coefficient. Consequently, the power factor of Bi 2 Te 3 thin films shows about 100% enhancement (14.9 μW·cm –1 ·K –2 @523 K) when the Δ α / α 0 increases up to 10%. This study demonstrates TE enhancement in thin films via controlled stress reduction, establishing a transferable framework for stress engineering across diverse material platforms. • Effective stress reduction is achieved via a single one-step magnetron sputtering method. • Role of intragranular defect formation in stress reduction investigated, offering deeper insight into stress regulation. • Ground rule between stress reduction and band structure is investigated, explaining enhanced thermoelectric response. • PF increased ∼100% over the unoptimized, ranking at leading level among existing magnetron sputtered Bi 2 Te 3 films.
Han et al. (Wed,) studied this question.